Hemostasis Koch 3

When it comes to vWD what are some things we see in classical cases? What will platelet count be? What is the TREATMENT we use and what does it do?

Classical cases reveal INCREASED bleeding time, DECREASED platelet adhesiveness; ABNORMAL ristocetin aggregation; also DECREASED factor VIII activity!!! (KNOW THIS!!!) • PLATELET COUNT IS NORMAL!!!! • Treatment is Desmopressin (DDAVP - induces increase in VIII and vWF) or cryoprecipitate (KNOW DESMOPRESSIN!!!!) • Acquired forms exist as well, but mostly vWD is inherited! Most COMMON inherited blood disorder REMEMBER!!! (remember inheritance, anemia, bleeding, petechiae, platelet problems evident should lead you to vWD!!!)

The next step is the release reaction (SECRETION). What is this induced by? What is released into the external milieu? Platelets also produce a POWERFUL PLATELET AGGREGATOR called what? Also SEROTONIN is released, what does this do?

Collagen Granule contents (including ADP and Ca++ from dense bodies) are secreted which cause further platelet aggregation. Thromboxane A2 (TXA2) (KNOW THIS!!!), which is a prostaglandin which is made via pathway on S23! Vasoconstrictor

In the intrinsic pathway what does factor IXa complex with, to cause what? What is special about factor VIII? (It is unclear how the intrinsic pathway is actually initiated in vivo, but we know this stuff happens in vitro) Deficiencies of XII, HMWK, or prekallikrein do not usually result in abnormal bleeding clinically, true or false? (KNOW THIS!!!!)

Complexes with Factor VIII, platelet factor 3 (phospholipid), and Calcium to activate Factor X!!! It is a COFACTOR NOT an ENZYME TRUE (May only see abnormalities of coagulation testing in this situation like prolonged PTT) (except factor XI has some minor bleeding problems)

When it comes to lab testing of blood vessel abnormalities, are there any specific for vessel problems/functions? What can lab tests be used for? What do we usually use to diagnose vessel problems? Overall Hereditary and Acquired Bleeding Disorders Associated with Vascular Abnormalities can be seen on S95! THIS IS GOOD SUMMARY SLIDE!!!

NONE are specific for vessel function although bleeding time MAY be abnormal secondary to underlying vessel disease rather than platelet dysfunction!!! - May be used to exclude other causes of bleeding!!! - Usually diagnosed by History & Physical!!! Biopsies may also be helpful.

As mentioned previously Hemolytic-uremic syndrome (HUS) is another disorder that causes the accelerated destruction of platelets/thrombotic microangiopathy. Generally who do we see this affecting? What is the clinical presentation of HUS? HUS most commonly follows GASTROENTERITIS caused by what bacteria?

» Generally a disease of children!!! (KNOW THIS!!!) » Clinical presentation • Microangiopathic hemolytic anemia • Thrombocytopenia • Prominent acute renal failure • Generally an absence of neurologic symptoms!!! (REMEMBER THIS!!!, so "Tyler is a psychotic while Homer is not") » E. coli O157:H7 (toxin causes endothelial injury)!!! But other bacterial infections can also trigger this entity!!! (KNOW THIS!!!) (usually don't want to treat with antibiotics, seems to make it worse!!)

When it comes to the general sequence of events for coagulation, what causes ARTERIAL VASOCONSTRICTION? What happens in PRIMARY HEMOSTASIS? In SECONDARY HEMOSTASIS, what initiates coagulation cascade? What is CLOT RETRACTION? All these events are virtually simultaneous. What do counter-regulatory mechanisms do?

Reflex neurogenic mechanisms and local factors (e.g. Endothelin), cause reduced blood flow. Injury exposes highly thrombogenic subendothelial extracellular matrix facilitating PLATELET ADHERENCE AND ACTIVATION → shape change of platelets and release of granule constituents → aggregation to form hemostatic plug! Exposure of Tissue Factor at site of injury (with factor VII), which leads to THROMBIN GENERATION and FIBRIN DEPOSITION, consolidating the platelet plug!!! Stabilization of the clot with CROSS LINKING of FIBRIN POLYMERS by factor XIII and contraction by action of thrombasthenin! They help limit the hemostatic plug to the site of injury, prevent clot extension and and remove the clot when vascular repair has been accomplished!!!

GOOD LIST OF ETIOLOGIES of QUANTITATIVE, THROMBOCYTOPENIAS and DRUGS implicated in thrombocytopenias seen on S136 and S137!!! (KNOW THIS FOR TEST, good review slide!!!)

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When it comes to bleeding disorders there are some important terms to know. What are Petechiae? What are Purpura? What are Ecchymoses? (KNOW THESE!!!)

- 1 to 3 mm circular red-purple, Pinpoint hemorrhage of skin or mucous membrane -3mm to 1 cm areas of skin or mucous membrane hemorrhage - Large areas of red-purple discoloration due to hemorrhage beneath the skin (bruise) - greater than 1 cm!!! (can be seen on S76)

When it comes to the COAGULATION SYSTEM, what are the various LAB testing available/used?

- Activated partial thromboplastin time (APTT or PTT)!!! - Prothrombin time (PT)!!! - Thrombin time (TT) - Activated clotting time - Specific factor assays - Dilute Russell Viper Venom Test (DRVVT) - Mixing studies!!! (like with consumable factors, BaSO4 factors) - Fibrinogen levels - Tests of fibrinolytic activity - Miscellaneous

When it comes to platelet abnormalities, we have Quantitative Disorders (decreased numbers thrombocytopenia), what could be the underlying problem? We also have Quantitative Disorders (Platelet dysfunction) due what kinds of underlying problems? We will look at both of these.

- Decreased production - Decreased survival - Splenic sequestration - Dilution (similar processes to what we saw in anemias) - Inherited - Acquired

Now we are talking about BLEEDING DISORDERS!!! These are diseases characterized by spontaneous bleeding or excessive bleeding after trauma!!! What can be some potential causes of this? (when RBC leave vessels is extravasation like petechia, purpura, etc.) When it comes to dealing with patients with BLEEDING DISORDERS, what is the MOST important thing to know?

- Increased vascular fragility - Vitamin C deficiency (scurvy, makes collagen), chronic glucocorticosteroid use (inhibit normal collagen formation like lupus people, asthma, inflammatory bowel disease people using glucocorticosteroids), etc!!! (GOOD TO KNOW!!!) (amyloid angiopathy in brain can cause bleeding too) - Platelet deficiency or dysfunction!!! (typically see petechiae)(or vWF disease can cause problem) - Derangement of clotting mechanism (inhibitors around in blood) - Derangement of fibrinolytic system HISTORY is extremely important!!! Also use physical and lab data to try to narrow it down to a vessel vs. platelet vs. coagulation/fibrinolytic system defect to guide further evaluation!

What are the Thrombin (IIa) actions? Which factor, once activated, CROSS-LINKS FIBRIN MONOMERS and stabilizes the fibrin meshwork? S44 shows Relative Rate of Thrombin Formation! What is the thing that massively increases the rate of Thrombin formation thus enhancing it? (KNOW THIS SLIDE)

- Platelet activation!! - Converts fibrinogen (I) to fibrin monomers + fibrinopeptides A & B (2 each)!!! - Potentiates positive feedback on V and VIII by allowing involved complexes to be formed at a much greater rate!!! - Positive feedback for greater activation of VII (and possibly XII) also occurs!!! - Forward activation of XIII!!! (GOOD TO KNOW these things!!) (all these things are happening at the same time) Factor XIII (KNOW THIS!!!) Platelet Surface!!!

What is the normal platelet function when trying to form a clot?

- Platelet adhesion and shape change - Release reaction (secretion)!!! - Platelet aggregation (cohesion)!!! - Contraction! - Platelets also interact with coagulation system!

Now we will talk about PLATELET DISORDERS!!! What are the Laboratory testing we usually do for platelet disorders? How can we do platelet counts? What is important to do if we see decreased count? What does peripheral smear used for? The basis for Bleeding Time is that If platelets are adequate in number with normal function, and vascular function is normal, a standard cut in the skin will stop bleeding in a standard length of time!!! What do we know about bleeding time studies? What is the Bleeding Time template method used? Bleeding time is prolonged by what? In the template method, Linear prolongation of bleeding time begins at between 80-100,000/mm3, with progressive prolongation as platelet count decreases (if platelet function is normal), true or false? Bleeding time can also be prolonged by what other things that mess with platelet function? (S101 shows how this test can be done; basically test used just to give us basic indication of platelet function) Bleeding time used INFREQUENTLY now because it is Time-consuming, Difficult to perform, Somewhat technique and operator dependent, Not always a good predictor of bleeding during surgery!

- Platelet count - Peripheral smear (can exclude thrombocytopenia due to clumping) - Bleeding time (screen of platelet function) - Platelet aggregation study (usually at large hospitals) - Platelet function assay (usually large hospitals have these) » Manual count with phase contrast microscope » Automated count by electronic or optical methods (part of CBC) Peripheral smear should confirm all decreased counts to be sure platelet clumping has not occurred (pseudothrombocytopenia)!!! (KNOW THIS!!!) For estimating count and observing morphology!!! Not a very tight or highly reproducible study. Not commonly used today, but I do see it used in several smaller hospitals whose labs lack more sophisticated forms of platelet function testing. • Standard incision (1 mm deep) made • Most reproducible technique (normal range is technique-dependent) • May leave a small scar • Bleeding time is prolonged by platelet dysfunction or low count!!!, +/- vascular abnormalities sometimes. (KNOW THIS!) TRUE (remember LINEAR prolongation as it decreases thus can estimate platelet function if count known) May also be prolonged in vWD (platelets can't adhere to collagen here), fibrinolytic states, afibrinogenemia (no fibrinogen; when platelets come together to make a mass fibrinogen is what keeps them together with Glanzmann receptors), and with ASPIRIN therapy (messes up platelet function, stops production of TxA2 which diminishes clumping of platelets)!!! (KNOW THIS!!!)

Platelets are produced in bone marrow from megakaryocytes (approximately 1000/cell). What is their approximation life span? 30-35% of the platelets are normally sequestered in the splenic pool — exchanged freely with the circulatory pool, what about in hypersplenism? What is the number of platelets in PB usually? What are bigger, young platelets or old platelets? What do we call the first interaction of platelets and vessels?

10 days There is INCREASED sequestration. Approximately 140,000 to 440,000 per mm3 (140-440 x 109/l) peripheral blood! Young platelets are larger than old platelets (MPV)! Primary Hemostasis!!!

In light microscope how do platelets look like? They have 3 types of SECRETORY GRANULES, what are they? Dense bodies are made of what things? What sorts of proteins are part of Alpha granules?

2 to 4 microns, round pale blue, granular cytoplasm (S17 and S18 have platelet structure picture) Lysosomes, Dense bodies (delta granules), and Alpha granules (proteins) ADP, Epinephrine, ATP, Histamine, Calcium, and Serotonin -Fibrinogen and fibronectin!!! -Platelet factor 4 (an anti-heparin) -Beta-thromboglobulin -Factors V and VIII!!! -Platelet-derived growth factor -Transforming growth factor-β

This is also a RARE inherited Autosomal Recessive disorder!!! We see GIANT platelets with MILD decrease in numbers. There is moderate bleeding seen and here the platelets LACK surface glycoprotein complex Ib- IX (vWF receptor)!!! It results in defective platelet adhesion!!! What is this disorder?

Bernard-Soulier Syndrome (KNOW THIS!!!)

More modern testing is PLATELET AGGREGATION! We know that platelet rich plasma is turbid/cloudy in nature. What do we add? What measures what happens? What can we evaluate through this, what sorts of things? (various aggregation studies seen on S104)

An aggregating agent is added (like epinephrine, ADP, collagen) Aggregometer measures the increase in light transmitted through less turbid plasma as platelet aggregates form and settle out. (it is becoming more clear, we can tell how fast they aggregate) Certain inherited and acquired qualitative platelet defects caused by diseases or drugs will show different patterns of aggregation over time with different aggregating agents!!! (GOOD TO KNOW!!!) (SEE S104 for different patterns we see Ristocetin which is an antibiotic that don't use bc caused thrombocytopenia, it causes vWF to bind much faster than when ristocetin is not around, causing increased aggreagation in body thus) (flat line on S104 shows ristocetin does not aggregate top 2 graphs bc it requires both vWF and normal BS receptors (Gp1b) and if does NOT aggregate even with ristocetin and vWF then we have BS syndrome; if when these 2 are used and we aggregate then that meant that vWF abscence)

The fibrinolytic/anticoagulant system exists to keep hemostasis in check and to dissolve clots once vascular injuries have been repaired! What is important to remember for these coagulation and anti-coagulation pathways? The physiologic response to vessel damage can be seen on S7 and S8!! So vessel damage initiates vasoconstriction, platelet activation, coagulation, and fibrinolysis.

A constant balance must be preserved between the pro-coagulant and anticoagulant systems!!! (KNOW THIS!!!) If the balance is tipped, Bleeding and/or Thrombosis may result!

The chief role of the extrinsic pathway seems to be to produce what? How is there amplification and reinforcement of this? There are various factors involved in the pathways. SEE S33 for a list of all the FACTORS!!! (KNOW THIS!!!) Also SEE S34 and S35 for the COAGULATION PATHWAY, KNOW THIS!!! The extrinsic pathway starts with what? From Factor X (10) down is what pathway? PT is what pathway and PTT?

A limited INITIAL BURST of THROMBIN activation after tissue injury!!! (tissue factor reacting with factor 7 causing thrombin activation) This activity is reinforced and amplified by a critical FEEDBACK LOOP whereby Thrombin activates Factors XI (11) and IX (9) ( of the INTRINSIC PATHWAY!!! (KNOW THIS!!!) Factor III aka Thromboplastin aka Tissue Factor (know all these names) Common pathway Extrinsic pathway; Intrinsic pathway (and both PT and PTT will measure the common pathway)

What is the common ACQUIRED platelet dysfunction we can see? What are some other things that can cause this to happen?

ASPIRIN prevents release reaction and secondary aggregation with resulting increased bleeding time!!! • Dysfunction lasts the lifetime of the platelet (irreversible)!!! (KNOW THIS!!!) (MOST COMMON in THE US, drug induced dysfunction of platelets!!!) » Other nonsteroidal anti-inflammatory drugs (NSAIDS!!!) (Indocin, phenylbutazone) inhibit platelets by same action as ASA, but LESS potent and Reversible action so depends on continuous blood levels!!! » Others including antihistamines, antibiotics, dextran, antidepressants, ethanol, etc. (SO know the history of the patient)(drugs affecting platelet function can be seen on S156) (KNOW ASPIRIN and NSAIDS)

von Willebrand disease (vWD) is an INHERITED disorder. What happens in this disorder? vWF and factor VIII are encoded by separate genes and produced by different cells, but circulate as a noncovalently bound complex, what does vWF do to factor VIII, which is another function of vWF in the blood? What is the von Willebrand factor (vWF, VIII:vWF) in blood basically? Does it exist as a huge protein or multimers?

Absence or dysfunction of von Willebrand factor (vWF) - a molecular complex which is necessary for both platelet function and factor VIII coagulant activity!!! (Platelets are actually normal in vWD, but the patient lacks functional vWF which is necessary for proper platelet function - particularly platelet adhesion to collagen via glycoprotein Ib-IX (BS receptor). vWF STABILIZES factor VIII - increases its half-life 6X (bound vs. free)!!! (so PTT can sometimes be prolonged in some cases of vWF disease) (complex can be seen on S141!!!) (Factor VIII: (VIII:C, VIII:AHF, VIII procoagulant protein is a Small fragment responsible for coagulant activity in clotting cascade; it is decreased or abnormal in hemophilia A, it is produced by hepatocytes) This is a much larger glycoprotein (99% of the complex) necessary for NORMAL PRIMARY HEMOSTASIS— it plays a key role in platelet adhesion to subendothelium. Exists NOT as a discrete protein, but as a series of high-molecular-weight MULTIMERS (containing up to 100 subunits) non-covalently bound to VIII (vWF is the largest soluble protein in plasma!!!).

The extrinsic is the short pathway. It can be seen on S38. It basically has Factor VII which is activated via Tissue Factor. Why is it called extrinsic? We need Extrinsic Factor for the PT test, which we get from rabbit brain. What part of the body of humans is Tissue Factor high? Thromboplastin (factor III, tissue factor) complexes with factor VII and, in the presence of what to activate Factor VII? Then what does this complex activate? What inhibits tissue factor activity? What do we actually know about Factor VII activation in the body?

Activation requires introduction of Tissue Factor (Thromboplastin, Factor III)!!! (KNOW THIS!!!), a substance produced by the TISSUES of the body and, hence, EXTRINSIC to the PLASMA!!! (KNOW THIS!!!) Tissue factor is present in high concentrations in skin, brain, lung, placenta, and in the adventitia of large blood vessels! Ca++ Factor X Tissue factor pathway inhibitor inhibits further tissue factor activity! VIIa is actually a potent activator of IX in vivo!!, and a weak activator of X!!! (KNOW THIS!!!!)

There are various Hemostatic control mechanisms to be aware of. What are some of the ANTIPROTEASES? What about if we switch Thrombin/Thrombomodulin? There are also PLASMA INHIBITORS, what are some of these? And we have FIBRINOLYSIS, what happens here?

Antithrombin and Tissue Factor Pathway Inhibitor (TFPI) Goes from procoagulation to starting to shutting it down. Protein C (activated by thrombin/thrombomodulin) and Protein S (cofactor in this) Activation of Plasminogen to form Plasmin to start chewing up the fibrin clot.

We can also use PLATELET FUNCTION ASSAY (PFA), what is this? What is result look like? What are the two aggregating agent combo's that can be used? This is a sequential process. First we use what and if abnormal what would we use? When we use Collagen/ADP, if it is abnormal then what? If this is normal then what does this indicate? What are some things that can mess up the PFA, caveats?

Automated test SIMULATING PRIMARY HEMOSTASIS. The result in, seconds, is the time required for the formation of a platelet plug with either of two aggregating agent combinations: • Collagen/epinephrine • Collagen/ADP First we use Collagen/epinephrine!!! It is highly sensitive to ALL platelet dysfunctions (will pick up any type of platelet dysfunction)! If abnormal, continue with collagen/ADP testing!!! (KNOW THIS SEQUENCE!!!) If abnormal, indicates PROBABLE TRUE PLATELET DYSFUNCTION!!! If normal, abnormal collagen/epinephrine assay is most likely due to ASPIRIN or aspirin-like effect!!! (KNOW THIS FACT!!!) • Platelet count < 70,000 may give falsely abnormal results • Hematocrits < 30% may give falsely abnormal results • Requires whole blood which is only stable for up to 4 hours after drawing!!! (KNOW THIS FACT!!!)

Then there is the platelet interaction with the coagulation system. Platelet activation induces expression of what? What is termed ACTIVITY in this situation? Activation allows for greater support of COAGULATION on the PHOSPHOLIPID SURFACE!!!! When it comes to platelet interaction with coagulation system, what is the POTENT PLATELET AGGREGATOR protein involved and what does it cause other than aggregation? The platelet plug is provisional, what does this mean? What is platelet factor 4?

Critical PHOSPHOLIPID BINDING SITES for calcium and coagulation proteins!!! PLATELET FACTOR 3; most steps of the coagulation sequence REQUIRE a phospholipid surface!!! - essentially represented by PF3. THROMBIN; also results in Fibrin Formation which serves to cement the aggregated platelets!! It will not remain hemostatically effective unless a firm fibrin clot forms around it!!! It is an anti-heparin.

Once activated, the coagulation cascade must be restricted to the local site of vascular injury to prevent clotting of the entire vascular tree, what if this doesn't happen what do we get? What are all the ways we accomplish this localization?

DIC (KNOW THIS!!! consuming platelets, clotting factors, and then start bleeding like crazy) - Localization of factor activation to sites of exposed phospholipids! - Blood flow dilution and removal of activated coagulation factors and unagglutinated platelets (in area of injury we get slowed blood flow so factors can come and work and on either side of this there is more fluid so factors are diluted) - Clearance of activated factors by reticuloendothelial system!!! - Self damping features (consumption of the consumable factors I, II, V, VIII, XIII)!

There are also some inherited platelet dysfunction disorders called Thrombopathies, also known as Storage Pool Disorders. What are they due to? These are a Wastebasket category of several inherited and drug induced disorders. They are extremely RARE!!

Deficient Release Reaction (secretion of)!!! (KNOW THIS!!!)

Another platelet abnormality that is also a QUANTITATIVE disorder are DRUG INDUCED DECREASE in PLATELETS! How can drugs cause decrease in platelets? What are the most common drugs that do this and what do they exactly do to the platelets? Also what other drugs may induce TRUE AUTOANTIBODIES, this is RARE though? Also a common consequence of Platelet Inhibitory Drugs that bind GPIIb-IIIa is drug induced decrease in platelets.

Drugs may DIRECTLY affect platelets or they can induce IMMUNE destruction. QUININE, QUINIDINE, and vancomycin!!! Bind platelet glycoproteins and somehow create antigenic determinants that are recognized by antibodies (KNOW THIS!!). GOLD SALTS (remember this as inducing ITP)

Balance between the anti- and pro-thrombotic activities of what determines whether thrombus formation, propagation, or dissolution occurs?

ENDOTHELIUM; after injury or activation is when endothelial cells acquire PROcoagulant activity. (Trauma, infectious agents, hemodynamic forces, plasma mediators, and cytokines)

What are the pathways of coagulation, which one is longer? Which pathway is more important physiologically when vascular damage has occurred?

Extrinsic and Intrinsic Pathways that converge on the activation of factor X!!! Extrinsic is shorter than the intrinsic pathway. (This is largely an artifact of our in vitro testing; actually lot of interactivity between the 2 pathways in vivo) The EXTRINSIC pathway is the most physiologically relevant pathway when vascular damage has occurred (releasing factor Tissue Factor that reacts with Factor VII (7))

We can also check for FIBRINOGEN!!! What are the 2 versions of this? We can also do tests for FIBRINOLYTIC ACTIVITY, what do these look for?

FUNCTIONAL and ANTIGENIC assays!!! (if we want to know if fibrinogen is present we use antigenic assay, if we want to know if it works then we do a functional assay) These look for Fibrin degradation (split) products or things like D dimers!!! These tests are: • Suggestive of fibrinolysis • Also detects fibrinogen degradation products

This is another factor deficiency. Its Frequency: about 1 per 80,000. It is Clinically INDISTINGUISHABLE from hemophilia A!!! There can be a wide spectrum of mutations. This disease is also X-linked Recessive!!! Bleeding into tissues will be seen like A. The laboratory tests will show: • Bleeding time, PT, TT: NORMAL!!! (again) • PTT prolonged and factor IX assay low!!! (good to KNOW!!!) What is this disorder? How do we treat this disorder? What about normal people or inhibitors in the body?

Factor IX Deficiency (Hemophilia B, Christmas Disease) • Minor bleeding: Supportive • Severe bleeding: Recombinant factor IX!!! » About 2-7% of hemophilia B patients will develop anti-IX antibodies (inhibitors)!!! » Some previously normal people will develop specific factor inhibitors as well

There are some important FEEDBACK-ACTIVATION mechanisms involving thrombin to KNOW!!! Thrombin can activate what factors also? Factor Xa can also activate what? Thrombin also activates what other factor allowing it to bypass other contact factors?

Factor V and VIII (increasing coagulation) Factor VII (thus activating the extrinsic pathway) Factor XI

Now we are at the COMMON PATHWAY, which can be seen on S41!!! Factor X as we know can be activated by either intrinsic or extrinsic pathway, which is why this is the common pathway. Here in this pathway what is the cofactor, similar to what we saw VIII as in the intrinsic pathway? Xa forms a complex with V, platelet factor 3 (phospholipid) and Ca++, collectively what is this known as? What does this act on?

Factor V is a COFACTOR!!! Prothrombinase!!! Prothrombinase acts on Factor II (Prothrombin) to produce Thrombin (IIa)!!! (KNOW THIS!!!) (KNOW THAT THROMBIN IS IIa)

We can also have INHERITED FACTOR DEFICIENCIES!!! This is the MOST COMMON hereditary disease associated with LIFE-THREATENING BLEEDING!!! It is an X-LINKED RECESSIVE (males & homozygous females), although SPONTANEOUS MUTATION accounts for up to 30% of all cases (no family history)(KNOW THIS)!!! The frequency: about 1 per 10-20,000. It Represents a reduction in the amount or ACTIVITY of factor VIII (8)!!! What is this disorder?

Factor VIII Deficiency (Hemophilia A) (KNOW THIS!!!)

What factors are LABILE (easily broken down) in STORED BLOOD? Also we know that ALL the factors are produced in the LIVER except which 2? Which factors are accelerators (cofactors), not enzymes? Which factor is inactive unless complexed with tissue factor?

Factors V and VIII (KNOW THIS!!!!) vWF: antigenic portion (carrier) of VIII (endothelial cells and megakaryocytes make this) And XIII (megakaryocytes make this with possible activation by liver) (so KNOW that vWF and 13 are NOT made by the liver!) Factors V and VIII Factor VII (7) needs TF (Strictly speaking, tissue factor could be considered a cofactor as well, with VII being the enzyme in this situation)

There are also Other Inherited Deficiency States. What are some these? (remember that remainder of factor deficiencies are rare, however, will cause clinical bleeding) (Other Less Frequent Factor Deficiency States can be seen on S189, GOOD REVIEW SLIDE!!!) (also Screening Tests for Congenital Coagulation Deficiency States can be seen on S190 also a GOOD REVIEW!!!)

Factors XII, Fitzgerald (HMWK), Fletcher (Prekallikrein) (contact factor)deficiencies are usually WITHOUT CLINICAL SIGNS OR SYMPTOMS (no bleeding seen in all of these, but XI would show bleeding!!!); result in isolated PTT INCREASES!!!

What are the CONTACT FACTORS? What are the contact factors activated by? When these factors are deficient what are the PT and PTT? Clinical bleeding in regards to these only happen with which factor? Are these factors stable in the serum? Are these absorbed by BaSO4 (screening test used to figure out what factors may be deficient sometimes)?

Factors XII, XI, prekallikrein, and HMWK!!! (KNOW!!!) Activated by foreign surfaces like collagen, glass, etc. (we know this happens in testing system at least) Normal PT and PTT will be increased. Factor XI YES they are!!! So when you have a clot they stay in the serum or when take blood and coagulate it, these factors will still be in the serum! They are NOT ABSORBED by BaSO4.

Then there is platelet aggregation (COHESION). At this time we are having platelet-platelet interactions and they stick together. What does this form? What is this process mediated by? What is it doing exactly? A disease in which there is Deficient Glycoprotein IIb-IIIa is called what? Platelet aggregation/cohesion is also induced via what things? What is one of these molecules that is used to test for von Willebrand Disease and Bernard Soulier Syndrome?

Forms the Primary Hemostatic Plug!!! (KNOW THIS!!!) FIBRINOGEN; this LINKS 2 platelets via receptor glycoprotein IIb-IIIa!!! (KNOW THIS!!!). This occurs after vessel injury. Glanzmann Thrombasthenia ("The pontiac GT had no Gas/Petrol left with only II Bottles of henny and III of Absinthe") » ADP, which also promotes further platelet ADP release! » Collagen » Serotonin » Thromboxane A2 » Thrombin » Epinephrine » Ristocetin!!! RISTOCETIN (KNOW THIS!!!)

This is a RARE inherited Autosomal Recessive disorder!!!! There is deficient platelet aggregation with the basic defect is deficiency or dysfunction of glycoprotein IIb-IIIa on the platelet surface!!! This affects platelet to platelet adhesion via fibrinogen!!! What is this disorder? (also if you don't have fibrinogen that can show up the same way)

Glanzmann's Thrombasthenia (KNOW THIS!!!)

We know that Thrombin does other things that haven't been mentioned yet. It has many PRO-INFLAMMATORY effects!!! What are some of the other things it does? (WBCs in clot also contribute to inflammation

Helps in Neutrophil adhesion, monocyte activation (which increases secretion of PDGF which causes proliferation of Smooth muscle which may be important in re-establishing vascular integrity), it activates lymphocytes, it can activate the Endothelium itself (which will cause the production of NO, PGI2, and tPA which are things that would stop coagulation), and it acts to cause platelet aggregation and release of TxA2 from platelets. Thus basically this shows that it has many other functions other than just making fibrin.

Thrombin Time (TT) is another test we can use. The TT is prolonged when substances are present which interfere with the action of thrombin on fibrinogen!!! What are some examples substances that cause this? What does Activated clotting time measure? We can also do specific factor assay testing, what is this? What does the Dilute Russell's Viper Venom Time (DRVVT) test do? What is it used to confirm usually? (KNOW THIS ONE FOR EXAM!!!)

Heparin, FSP's, abnormal fibrinogen, t-PA, streptokinase, urokinase. (KNOW THESE!!!) » Measures platelets and all factors except VII and XIII!!! (just like PTT) » Useful in monitoring HEPARIN THERAPY We can order assays for specific single factors like VIII for hemophilia A, IX for hemophilia B, etc. Russell viper venom directly activates Factor X (KNOW THIS!!!)(that's why snake venoms can cause thromboses). It is used to confirm the presence of an ANTIPHOSPHOLIPID ANTIBODY (APA) — if still significantly prolonged when mixed with normal plasma, considered indicative of an APA!!!! (KNOW THIS!!!)(remember normally coagulation happens most rapidly on phospholipid surface, so Abs make this clotting take much longer) (so remember clinically it causes thromboses, can see spontaneous abortions, etc. but when we do a PT test as screen it looks like a bleeding disorder bc prolonged PT is seen. It is prolonged bc the antibodies are messing up the clotting system!!! So NOT a BLEEDING DISORDER but RATHER A CLOTTING DISORDER)(the DRVVT actually bypasses all the intrinsic steps since it goes and activates X, but if there are antiphospholipid antibodies those have taken away phospholipids and the DRVVT will show prolonged time also and tell us it wasn't a problem with those intrinsic factors themselves but rather antibodies attacking the phospholipid!!!) (KNOW THIS FOR EXAM FOR SURE!!!!)

This is a drug induced decrease in platelets. It occurs in approximately 5% of patients receiving heparin. MOST DEVELOP TYPE I thrombocytopenia when this does happen!!! This has a RAPID onset, modest severity, it can be clinically insignificant, it may resolve (even with out stopping heparin), and it is probably due to HEPARIN-INDUCED PLATELET AGGREGATION!!! (KNOW THIS!!!) What is this problem?

Heparin-Induced Decreased PLTs (HIT)!!!

This is a blood vessel abnormality due to structural vascular abnormalities. It is Autosomal Dominant, with high penetrance!!! We see multiple telangiectasias of skin, mucous membranes, and viscera - especially the nose, tongue, mouth, eyes and GI tract -hemorrhage in these areas due to the abnormal vessels!!! (KNOW THESE AREAS!!!). This is associated with pulmonary arteriovenous malformations (AVM). The disease becomes worse with age. What is this disease?

Hereditary Hemorrhagic Telangiectasia (Osler-Weber- Rendu disease)!!! (SEE S87 for good picture)

What are the CONSUMABLE FACTORS? Are they found in serum? Are these absorbed by BaSO4?

I, II, V, VIII, and XIII are consumed in clotting (1,2,5,8, and 13) (I is fibrinogen). These are activated by THROMBIN. NO; They are present in PLASMA but NOT in serum!!! (remember consumable not in serum, only in plasma) NO they are not. (remember consumable ones are not absorbed!!!)

What are the Vitamin K-dependent (Prothrombin) Factors? What is our major source of vitamin K? We need vitamin K for production of fully active proteins. Are these absorbed by BaSO4? Are they absorbed by anything else? All these are found in the serum, EXCEPT which factor is not in the serum? Factor II is prothrombin and is consumed by what?

II, VII, IX and X (2,7,9,and 10) (KNOW THESE FOR THE EXAM FOR SURE!!!) They come from the gut, bacteria in the bowel will make most of our vitamin K. So iatrogenically we could cause vitamin K deficiency by someone on prolonged Antibiotics!!! So all of a sudden they have developed a bleeding disorder!!! (KNOW THIS!!!) YES they are. ; Also absorbed by Al(OH)3 Except for Factor II!!! It is consumed by COAGULATION.

This is a quantitative disorder which has Accelerated Destruction of platelets. It would be similar to something like autoimmune hemolytic anemia, similar process. It is fairly common platelet disorder. There are Primary/idiopathic form. Also the secondary form may occur in things like: • SLE • Viral infections, including HIV • Various B-cell neoplasms • Certain drug therapies What is this disorder? What kind of autoantibody do we see usually? What can be done to induce remission?

Immune (Idiopathic) Thrombocytopenic Purpura (ITP) (KNOW THIS!!!) (antibodies against own platelet antigen) Autoantibody (usually IgG!!!) directed against platelets (usually against GPIIb-IIIa or Ib) resulting in removal by the spleen!!! (KNOW THIS!!!); Very much like AIHA (SPLENECTOMY induces remission in more than 2/3 of patients) (antibody coated platelets not removed bc spleen not there and also no spleen so less antibody production)(peripheral smear will show Howell-Jolly bodies)

Normal vessels depend on platelets for integrity, DECREASE in platelets or platelet function results in what?

Increased Capillary Leakage, leading to PETECHIA!!! (good TO KNOW!!!)

So Activation of Plasminogen to Plasmin is done by Plasminogen activators!!! What are the INTRINSIC plasminogen activators to be aware of? When it comes to Plasminogen activators that are EXTRINSIC, what is the main one we think of? What produces t-PA and when is it released? It has a low effect on plasminogen in the absence of what and why is this important?

Involvement of XII, prekallikrein, HMWK and plasminogen proactivator!!!! (remember that these were some of the contact factors seen in the Coagulation cascade activation ALSO!!!) (KNOW THIS!!!!) Plasminogen activator is released from tissues (tissue plasminogen activator or t-PA)!!! It is produced by endothelial cells; released during Exercise, or in response to vascular occlusion, epinephrine (platelets can release Epi), etc; It has little effect on plasminogen in the absence of FIBRIN - keeps fibrinolytic activity near site of thrombosis!!! (KNOW THIS CONCEPT!!!) We also have Urokinase-like PA!!!; present in plasma and various tissues; can see this in the urine as well

What is the CLINICAL PRESENTATION of Hemophilia A? What is usually the most troublesome problem with people with hemophilia A? What are some other complications? (KNOW THESE characteristic complications!!!) (good pictures on S181-182!!!)

It is Dependent somewhat on the severity of the defect (several different genetic lesions have been identified; <1% of normal activity - severe, 2-5% - moderate, 6-50% - mild and shows up late)!!! • HEMARTHROSES (sometimes spontaneous) represents the most troublesome problem!!!; most severe hemophiliacs suffer progressive deformities with crippling degenerative joint disease (destroying articular cartilage)!!!! (GOOD TO KNOW!!!) (will feel like ball of fluid, and aseptically aspirate it to make sure its blood) • Intramuscular hemorrhage!!!, particularly following trauma • Post-operative bleeding!!! • Delayed and prolonged bleeding following minor surgery or lacerations!! • Bleeding often NOT present at birth (milder forms)!! • CNS bleeding represents 30-50% of deaths!!! (KNOW THIS!!!) • Petechiae are characteristically ABSENT (platelets are normal)(rather bleeding into tissues, hematomas!!!)

The Euglobulin clot lysis test is used for what? What happens in it? There are also other miscellaneous assays we can use to check for the presence or absence of certain things, what are some examples? Also S176 just shows the Coagulation Assays in Preterm and Term Infants as Compared to those of Adults and Older Children, which shows that at different ages we have different tests and values.

It is a test of fibrinolytic activity!!! -Portion of plasma (excluding plasminogen activator inhibitors ) is caused to clot and then allowed to lyse — if the fibrinolytic system has been already activated, lysis will occur sooner!!! (very rare to use this!!!) » Anti-thrombin III (AT III) » Protein C » Protein S » Clot stability in 5M urea • Abnormal in XIII abnormalites

von Willebrand factor (vWF, VIII:vWF) may be absent or abnormal in vWD!!! and this may be accompanied by what? Where is vWF made? vWF includes the Ristocetin cofactor (VIII:RCo), what is this necessary for? (Nomenclature of the F-VIII/von Willebrand Factor Complex can be seen on S145!!! good to know; good picture on S146 also)

It may be accompanied by secondarily decreased VIII and a prolonged PTT!!! (KNOW THIS!!!) (but not always an increased PTT) Produced by endothelial cells (and megakaryocytes)!!! (one of the ones that is NOT made in the liver) That portion is necessary for aggregation of platelets induced by the antibiotic Ristocetin!!! (REMEMBER Weibel-Palade bodies in endothelial cells have the vWF!!!!!)

What is Coagulation? (in the process of secondary hemostasis) What encases the platelet plug? Fibrin is cross-linked and stabilized by what factor and what does this create? In the process of coagulation each reaction results from the assembly of what 3 things? Where are these components assembled?

Its a series of transformations (a cascade, sequential and simultaneous) of proenzymes to activated enzymes culminating in the formation of thrombin, which converts SOLUBLE FIBRINOGEN to an insoluble FIBRIN GEL!!! Fibrin gel Factor XIIIa!!!, this leads to secondary hemostasis. (KNOW THIS!!!!) - An enzyme (activated coagulation factor) - A substrate (proenzyme form of a coagulation factor) - A cofactor (catalyst/accelerator) Components are assembled on a phospholipid complex with interaction of calcium ions!!! (on the platelets) (this helps to keep clotting localized (e.g. to the surface of activated platelets and endothelium)) (KNOW THIS FOR EXAM!!!)

What does Activated partial thromboplastin time (APTT, PTT) measure? (remember VIII in hemophilia A was diminished, IX in B; so both will have prolonged PTT) PTT Measures the time needed (in seconds) for citrated plasma to clot in the presence of what? What do we use PTT to diagnose usually?

Measures INTRINSIC and common pathways!!! -All factors except VII and XIII!!! (KNOW THIS!!!) Platelet activity NOT measured. Kaolin (activates XII), phospholipid, and calcium!!! (KNOW THIS FACT!!!) Used to diagnose and monitor coagulopathies, assessment of antiphospholipid antibodies and to MONITOR HEPARIN THERAPY!!! (KNOW THIS!!!)

We also know that DILUTIONS can cause quantitative platelet disorders. When do we usually see this happen and why is it a problem? What may the patient need in such situations when platelets have been diluted?

Massive RBC transfusions!!! Packed RBC's used to replace lost RBC's, this product does not contain significant platelets!! Large volumes of these packed RBCs (20+ units) dilute the body's platelets leading to thrombocytopenia!!! » Therefore may need platelet transfusions in this situation!!! (6 pack or 1 pack) (KNOW THIS!!!)

What do we usually see in BLOOD VESSEL ABNORMALITIES? Occasionally may cause more significant findings such as what? There are also other things that are areas of further investigation. What is an example of an autoimmune vascular injury? We can have Structural vascular abnormalities in like the brain, like what? There are also miscellaneous things that can cause blood vessel abnormalities like what? What would lab tests look like for blood vessel abnormalities?

Most often induce Petechiae and Purpura in skin or mucous membranes!!! (KNOW THIS!!!) » Hemorrhage into joints, hematoma in muscles, subperiosteum » Menorrhagia (menstrual bleeding), epistaxis (nose bleed), GI bleeding, or hematuria Leukocytoclastic vasculitis (fragmented neutrophils deposition in small blood vessels wall)!!!! (KNOW THIS!!!, it usually shows up as palpable purpura) AVM (arteriovenous malformation) Vitamin C deficiency, steroids, etc. The coagulation studies would be normal. Platelet function would be normal.

When it comes to Lab testing in Hemophilia A, what will Bleeding time, PT and TT look like? What about PTT? Some of these carriers can be identified how? Testing by what allows 100% identification of carrier state? How do we treat Hemophilia A? This can also be complicated where body has developed INHIBITORS to Factor VIII. What happens here? Also some previously normal people will develop specific factor inhibitors as well (e.g. anti-VIII), but usually rare. (Ecchymosis in Acquired Factor VIII Inhibitor Patient can be seen on S185!) (KNOW HEMOPHILIA A FOR THE EXAM!!!)

NORMAL!!! (bc it is not a platelet disorder) PTT prolonged and FUNCTIONAL factor VIII assay LOW!!! 80-90% of carriers can be identified by an INCREASED ratio of vWF to VIII!!! (while decreased vWF would decrease stable VIII and bleeding time would be affected, here vWF is plenty and we have normal platelets) Testing by DNA probes!!!! (good to know!!!) • Mild bleeding: Supportive!!! • Serious bleeding: Recombinant factor VIII!!! • Approximately 10-30% of patients (particularly those with severe deficiencies) will develop antibodies that bind to and inhibit VIII (independent of the source of VIII - can become refractory)!!!

Other quantitative platelet abnormalities are Splenic Sequestration (Hypersplenism)!!! Normally how many platelets can be stored in the spleen? What happens in Splenomegaly?

Normally 30-35% of circulating platelets are stored in the spleen! In splenomegaly up to 80-90% are trapped here and may lead to clinically significant thrombocytopenia!!! (KNOW THIS!!!)

One important thing that the fibrinolytic system does is the activation of PLASMINOGEN to PLASMIN, what does this cause? Why is fibrinolysis NORMALLY restricted to the clot? What are the two main enzymes that allow for this localization of fibrinolysis in the clot area? Plasminogen activators are present in what locations? Remember that free plasmin is rapidly inactivated by what? (KNOW THIS!!!)

Plasmin is a protease which degrades fibrin into fibrin-split products (FSPs)!!! (PLASMIN is needed to break down a clot bc it breaks down fibrin) Because inhibitors to Tissue-plasminogen activator (t- PA) and Plasmin are present in circulating blood!!! • Plasminogen activator inhibitors!!! • Alpha 2-antiplasmin (Plasmin inhibitor) !!! (prevent plasmin from doing its job outside from the clot area) (GOOD TO KNOW THESE!!!) They can be: » Intrinsic » Extrinsic » Exogenous α2-antiplasmin!!! (KNOW THIS!!!) (so any plasmin that is free in areas of no clot are chewed and inactivated)

The intrinsic pathway can be seen on S36! What does it start with? What does HMW-K Kallikrein activate to start the pathway off? Any abnormalities in these (called the distal factors) will cause what? Clinically which factor of this is the only one that causes significant bleeding?

Prekallikrein and HMW-K (high molecular weight kininogen) which make HMW-K Kallikrein Activates factor XII (12)!!! Will prolong the PTT test!!! (KNOW THIS!!!) Factor XI

Antiproteases control coagulation. Where is ANTITHROMBIN (AT III) produced? What is the main action of AT III, what 2 factors are inactivated by it? What does it inactivate to a lesser extent? How is AT III activated? How can this process be greatly accelerated? AT III levels decrease with in vivo or in vitro coagulation, true or false?

Produced in the liver and is NOT vitamin-K dependent. It causes IRREVERSIBLE binding with and inactivation of Thrombin and Xa!!! (so stops product and pathway) To a lesser extent inactivates IXa, XIa, XIIa, kallikrein and plasmin. Activated by binding to heparin-like molecules on endothelial cells! (KNOW THIS!!!); reaction greatly accelerated by HEPARIN but REMEMBER (Heparin won't do anything if AT III is absent!!!) TRUE

There are blood vessel abnormalities due to miscellaneous things. There is a disease which is characterized by different types including Schamberg's purpura, Majocchi's purpura, and Gougerot-Blum purpura. Histologically, there is inflammation and hemorrhage WITHOUT fibrinoid necrosis of vessels! What is this disease? Also Infections (mechanisms may include vasculitis and/or DIC). What are some examples of these that can cause these things? We can also have Drug reactions which are usually immune complex-mediated!!

Purpura Simplex » Bacterial - Meningococcemia (purpura with this SEE S92) » Rickettsial - Rocky Mountain spotted fever (petechiae can be seen with this on S93) » Viral - e.g. Measles

When it comes to the activation of plasminogen to plasmin by plasminogen activators, there are some THERAPEUTIC AGENTS that are important to know about. This is a bacterial enzyme that activates INDIRECTLY by forming complex with plasminogen or plasmin to activate other plasminogen - 1 time use only (immune recognition after using once)!!What is this that we use sometimes? This is a Protease found in urine and plasma, it DIRECTLY activates plasminogen to plasmin! What is this that can also sometimes be used? This is a therapeutic agent that we use most commonly! There are many Recombinant forms now available. It is the major agent here with use in thrombotic events such as Myocardial infarctions, non-hemorrhagic strokes, pulmonary emboli? What is the ANTIDOTE for this? (can use these things like these in MI, stroke, caused by certain clots, non-hemorrhagic in nature we want to get rid of these clots/dissolving clots; contraindicated in hemorrhagic bc we would only get more bleeding)

STREPTOKINASE UROKINASE t-PA (KNOW THIS!!!) Aminocaproic acid (used to reverse t-PA)

The D-DIMER TEST is very IMPORTANT!!!! This test is Similar to FSP test EXCEPT it is specific for what? A normal quantitative D-dimer test can be used to help EXCLUDE what in the APPROPRIATE SETTING like an ambulatory, out-patient setting? (D DIMER ONLY GIVES YOU USEFUL INFO IN AN ANBMULATORY PATIENT, not a chronic hospitalized patient) So what are some things that can cause an ELEVATED D-Dimer?

Specific for fibrin fragments which have been previously covalently linked (by XIIIa)!!! (KNOW THIS!!!) Thus indicates that both fibrin cross-linking and fibrinolysis have occurred!!! (meaning you have established a stable clot somewhere in the body) deep venous thrombosis (DVT's)!!!! (A negative test means they don't have a clot so gives you solid information, while a positive test means you will have to go to another test to rule out a DVT for certain!!!) (KNOW THIS TEST FOR THE EXAM!!!!) • Trauma or surgery within the last four weeks • Large hematoma, arterial thrombosis • Disseminated malignancies • DIC • Sepsis, severe infections, pneumonia • Liver disease, cirrhosis • Pregnancy • Diabetes • Atherosclerotic vascular disease • Sickle cell disease • Advanced age (>60 years) • Fibrinolytic therapy within the previous seven days • General hospitalization (thus the test doesn't have much value in these situations!!! don't waste patients money on this)

The first step involves platelet adhesion and shape change, in which there are platelet-vessel wall interactions occurring. At this time platelet must overcome the high shear forces of flowing blood. Adhesion is the ability to stick to a foreign surface, what can this be? The disk shape is also lost and what forms? There are bridges between glycoprotein Ib (Ib-IX) of platelet and subendothelial collagen, what mediates this process? What is Bernard-Soulier Syndrome!!!? (good picture on S21!!!)

Subendothelial collagen after vessel damage. Pseudopods formed Mediated by vWF!!! (KNOW THIS!!!) Deficient Glycoprotein Ib (KNOW THIS!!!) ("He thought it was BS to not get 1B in at least one class")

What are the symptoms we see for ITP? (S118 HAS A GOOD TABLE to COMPARE ACUTE VS CHRONIC ITP, good to know for TEST!!!)

Symptoms are those of ANY thrombocytopenia!!! Such as: • Petechiae and ecchymoses!!!(most common in lower legs bc highest venouse pressures here, leakage, palpable purpura) • History of easy bruising • Epistaxis • Bleeding from gums and soft tissues following minor trauma • May manifest first with melena (blood in feces), hematuria, or menorrhagia (mucosal bleeding)!!! • Intracranial hemorrhage is RARE IN TREATED patients

What do endothelial cells make that allow for platelet interactions? What do ECs make to allow for coagulation system interactions? What do ECs make that allows for fibrinolysis interactions? These things FAVOR THROMBOSIS. GOOD PICTURE OF FUNCTIONS OF ENDOTHELIAL CELLS on S12 and S13!!!

Synthesis and secretion of von Willebrand factor (vWF)!!! (Essential for platelet adhesion - not specifically synthesized after injury — ALWAYS present in Weibel-Palade bodies!!!) (KNOW THIS!!!) Release of TISSUE FACTOR in response to cytokines (TNF, IL-1) or endotoxin!!! — activates EXTRINSIC PATHWAY!!! Also they have Binding Sites for coagulation factors!!! (more active when bound) Secretion of Inhibitors of Plasminogen Activator!!!

We have many Etiologies of Thrombocytosis, which is TOO MANY PLATELETS. There are both PRIMARY thrombocytosis and SECONDARY (reactive) thrombocytosis and Transient thrombocytosis. What do we see the primary thrombocytosis in? What about the secondary thrombocytosis? What about transient thrombocytosis?

The Myeloproliferative diseases like PV, CML, ET, MF sometimes. (chronic GI blood loss can be seen, high platelets but don't work so thromboses, iron depleted marrow) (KNOW THIS FOR EXAM!!!!)(tyrosine kinases are mutated in these ones, causing abnormal proliferation) Acute hemorrhage, surgery, post splenectomy, recovery from thrombocytopenia, malignant diseases, chronic inflammatory disease, IRON DEFICIENCY anemia (microphilic, hypochromic anemia), hemolytic anemia. Vigorous exercise, Epinephrine, and childbirth. (can see list S159 for the list)

When it comes to both TTP and HUS, though both are somewhat similar to DIC (MAHA), these illnesses are distinct! What is the PT and PTT in these? Can both of these be fatal? (KNOW THESE FOR EXAM FOR SURE!!!!) (LOOK AT S130 and S131 for lab results are good REVIEW SLIDES FOR THESE!!!) (remember these are a platelet problem, not a coagulation problem)

The PT and PTT are most usually NORMAL or minimally elevated (both are markedly abnormal in DIC)!!! TTP and HUS can both be fatal! -- Be on the lookout!!! (KNOW THIS!!!) (look at S131)

During platelet contraction what happens? The ultimate result of this forms what?

The cytoskeleton contracts, Draws platelet aggregate together into an IRREVERSIBLY FUSED mass of platelets!!! This mass forms the Secondary Hemostatic Plug!!! (KNOW THIS!!!)

Intact blood vessels are made of ENDOTHELIAL CELLS. What are some of the main properties of endothelial cells? How are the endothelial cells antiplatelet? What sort of things do they make to have this function? What sorts of things make ECs anticoagulant? What gives ECs their fibrinolytic qualities? These things INHIBIT THROMBOSIS.

They are Antiplatelet, Anticoagulant, and Fibrinolytic! Insulate platelets from highly THROMBOGENIC subendothelial components (extracellular matrix, collagen). Production of PROSTACYCLIN (PGI2) and NO which inhibit platelet aggregation and cause VASODILATION!!! - Heparin-like molecules!!! (membrane-associated) — potentiation of antithrombin III (AT III) - Thrombomodulin!!! — involved in activation of protein C - Tissue factor pathway inhibitor!!! — inhibits TF-VIIa and Xa Synthesis of Tissue Plasminogen Activator (t-PA)!!!

What is Protein S? What is its main function? (also fyi, protein S circulates in a free, active form and an inactive form, bound to C4b-binding protein; also there are numerous other inhibitors of the coagulation factors also appear to be present but are not well defined at present)

This is also a VIT K-DEPENDENT PLASMA INHIBITOR that is produced in the liver. Cofactor of protein C (needed to inactivate Va and VIIIa)!!! (KNOW THIS!!!). Binds to the endothelial cell surface and acts as a receptor for APC.

When we are talking about Blood vessel abnormalities - Autoimmune vascular injuries, we have something called Henoch-Schönlein purpura (Microscopic polyangitis), what is this? What is the clinical manifestation of this? (KNOW THIS!!!) Any immune complex-mediated condition or vasculitis may result in a purpura-like picture, true or false?

This is an Immune complex-mediated process with generalized vasculitis! We usually see in children following infections, insect bites, and drug exposures!!! (KNOW THIS!!!) (GOOD PICTURE ON S84!!!) • Urticarial lesions (rash) • Bowel wall hemorrhages with colicky abdominal pain • Acute glomerulonephritis • Arthralgias This is TRUE!!!

Another antiprotease is the Tissue factor pathway inhibitor (TFPI)!!! Where is this released from and what does it do?

This is released from endothelium cells! It inactivates TF-VIIa and Xa!!! (GOOD TO KNOW!!!)

What do we know about the FIBRINOLYTIC SYSTEM? What is the fibrinolytic system composed of and what other system does it cooperate with?

This is the system that gets rid of a clot. Converts insoluble fibrin clot to Soluble fragments! Remember that the formation of fibrin is essential in wound healing and hemostasis, but its eventual removal is equally important!!! (KNOW THIS!!!) The fibrinolytic system is the major physiologic means of disposing of fibrin after its hemostatic function has been fulfilled. This system ALSO stops further fibrin polymerization and helps control coagulation away from the clot, keeping it localized!!! Composed of activators and inhibitors in a delicate balance!! Functions cooperatively with the coagulation system!!! Both may be triggered by the same mechanism. Formation of fibrin greatly enhances activation of fibrinolysis!!

When it comes to quantitative disorder, this is like anemia, in that it is a SIGN and NOT a disease. It is characterized by Platelet count <140,000/mm3. It may be due to Accelerated destruction!!, Decreased production!!, and/or sequestration of platelets, Splenic sequestration, and rarely dilutional (like in massive transfusions)!!! What is this sign?

Thrombocytopenia

Another important control of coagulation is Thrombin-Thrombomodulin! We know thrombin has many different functions, the main being the production of fibrin. We want thrombin to be doing these things where the injury is but not in other normal places of the body. Any thrombin that escapes the area of the clot formation will reach an area with intact, "healthy" endothelium, which expresses what? What does this thrombomodulin do to thrombin?

Thrombomodulin Thrombomodulin essentially converts thrombin to an anticoagulant instead of a procoagulant!!! As the thrombin-thrombomodulin complex activates protein C, which inactivates Va and VIIIa!!! (inactivating the cofactors needed for coagulation) (KNOW THIS!!!!)

What is normal hemostasis? What are pathologic features that can affect hemostasis? Hemostasis requires proper function of three contributors, what are they?

Tightly regulated processes that maintain blood in a fluid state in normal vessels, yet also permit the rapid formation of a hemostatic clot at the site of a vascular injury and subsequent lysis of the clot after vascular repair has been accomplished. Thrombosis (clot formation within intact vessels) and Bleeding Disorders • Vessels and the vascular endothelial cells • Platelets • The coagulation/fibrolytic systems

Also Age at onset may be characteristic of certain disorders. Hemorrhagic disease of the newborn is usually due to what is usually seen SHORTLY AFTER BIRTH? (bleeding from umbilical stump bc 2,7,9,10 and C and S diminished) Hereditary coagulation disorders may not present until middle age, particularly in milder forms (like hemophilia A). Hemorrhagic telangiectasia frequently presents when? (dilated fragile abnormal vessels) Drug ingestion history is extremely important, true or false? (KNOW THIS!!!)

Vitamin K deficiency Middle Age TRUE

When Plasmin acts on Fibrinogen or Fibrin, it will split either of them, this leads to what? Similar products formed whether fibrin or fibrinogen degraded, but what is the main EXCEPTION to remember where you see something different and what are these things called? What disease do we see this in usually? SEE S69 for a good picture of the process along with S70-72 showing all the steps in regulation that we talked about!!! (also seen in the picture is the fact that even Thrombin itself can cause release of plasminogen activators)

We get the formation of fibrin(ogen) degradation products (FDP, FSP - fibrin split products)!!! FSP, once released, further serve as anticoagulants (helping to turn off coagulation)! In a situation where there is clot formation with CROSS-LINKING the products of degradation we get are D-Dimers which is used to evaluate for possible DVT's - formed only from cross-linked fibrin!!! (KNOW THIS FACT!!!!) (usually in deep muscles of calves, lower extremities, pelvic veins in women sometimes; these are in deep veins of legs and the superficial ones not to worry bc they don't embolize)(we can detect via antibodies the D-Dimers in the blood which is good for evaluating the presence or absence of clotting in the person)

Lets say we have One or more factors are missing in a patient's blood, meaning they will have abnormal PT and/ or PTT. If we give them the factor back the problem should go away. So what do we do if we think they have a factor missing? So if this fixes it, what do we give next to figure out what it is? What will this have missing? If the serum corrects it we know it is not one of the factors that were not there. So we can eliminate those factors from the culprit. What do we give next? What is deficient in this? What are these studies called? If there is NO CORRECTION by PLASMA, what does this suggest? (KNOW HOW THIS WORKS, ON THE TEST!!!)

We give them POOLED PLASMA which contains all the factors. And if this corrects it we know something is missing in the patients blood. We give them SERUM. Serum does not have the consumable factors, so factors 1,2,5,8 and 13!!! ADSORBED PLASMA; absence of 2, 7, 9, and 10 because BaSO4 is put in this plasma and takes these things away (takes away the Vit K factors) Mixing Studies (Mix patient with each, re-run the abnormal coagulation test and look for correction) This suggests there is an INHIBITOR of a factor somewhere. (SEE S50 for this information)

When we see Ecchymoses and petechiae in AML patients, what should we suspect usually?

We suspect a PLATELET ABNORMALITY. (See S135)

There are also Plasma Inhibitors like Protein C as we had mentioned. Is this a vitamin K dependent protein? How is this involved in modulating? What is special about factor V? APC has been used to treat Sepsis patients, true or false? (we usually heparinize a patient and then start on coumadin/warfarin bc then don't have paradoxical clotting which we can see with coumadin which is decreasing C and S vit. K dependent inhibitors before decreasing the other vit K dependent, just fyi) (remember 2, 7, 9, and 10 and C and S are all vit K-dependent)

YES it is and it is produced in the liver. Endothelium-associated thrombomodulin and thrombin form a complex on the endothelial cell surface to activate protein C (APC) and this complex, with additional cofactors, inactivates factors Va and VIIIa!!! Factor V (not Va) acts as one of the cofactors for activated protein C (APC) — "APC cofactor", so it is a cofactor for coagulation and anticoagulation. True it has been used to try to treat sepsis patients.

Large solitary ecchymoses, hemarthroses (bleeding in joints, deep hematomas, and delayed bleeding phenomena are all common for what? Petechiae, multiple small ecchymoses, persistent bleeding from superficial cuts and scratches, epistaxis, and menorrhagia at menarche are common in what? X-linked recessive inheritance pattern is common in what?

common with COAGULATION DISORDERS (can be fibrinolytic problems), but are rare with platelet or vessel abnormalities. PLATELET DISORDERS (platelet numbers or platelet function; can be seen with someone using Aspirin, VW disease also) COAGULATION DISORDERS again like hemophilia.

We can also have quantitative disorders of platelets due to HIV-associated Thrombocytopenia!!! One of the most common hematologic manifestations of HIV infection is this. Infection decreases platelets by two separate mechanisms, what are they? (KNOW THIS!!!)

» IMPAIRS platelet PRODUCTION (via CD4 on magakaryocytes!!!) » Causes INCREASED DESTRUCTION (via autoantibodies secondary to B-cell dysregulation, down regulation of immune system in HIV)

What is Prothrombin Time (PT) used to measure? PT measures the time needed (in seconds) for citrated plasma to clot in the presence of exogenously added what? What are the major clinical uses for PT? (both PT and PTT areas covered seen on S164!!!) (so KNOW which specific test you order for a specific disorder, and we can see the clotting factors evaluated by each of the tests on S165 also!!!)

» Measures EXTRINSIC and common pathways!!! • Does not measure intrinsic pathway, factor XIII, or platelet function!!! Tissue Thromboplastin (tissue factor and phospholipids) and calcium!!! (KNOW THIS!!!) • Monitor oral anti-vitamin K therapy (Coumadin)/Warfarin!!! (KNOW THIS!!!) • Diagnose and monitor vitamin K deficiency!!! • Diagnose and monitor inherited factor deficiency (II, VII, IX, X) • Manage dilutional coagulopathy (if you don't have enough factors it gets elongated) • Diagnose and monitor other acquired coagulopathies (DIC!!!, liver disease, etc.) (DIC will also be prolonged!!!) (for liver disease both PT and PTT are prolonged bc all factors except for XIII and vWF come from the liver)

Thrombotic thrombocytopenic purpura (TTP) is most commonly seen in what people? What is the CLASSICAL PENTAD for this? What do we think are the initiating mechanisms for TTP? The Primary Form of TTP is secondary to an enzyme INHIBITION/DEFICIENCY, what is the enzyme? What does this enzyme deficiency result in? What would inhibitor forms to this enzyme be treated with? Secondary forms may be related to forms of endothelial injury, not well understood at the present like what?

» Most common in ADULT FEMALES!!! » Classical pentad: • Fever • Thrombocytopenia • Microangiopathic hemolytic anemia • Transient neurologic deficits!!! (KNOW THIS!!!) • Renal failure (other 4 can be seen in HUS too) Endothelial injury and activation of intravascular thrombosis, activating platelets preferentially!!! ADAMTS13 (either deficient or an inhibitor to this) Resulting in circulation of ultra-large vWF MULTIMERS that promote platelet activation and aggregation nearly spontaneously!!! (KNOW THIS!!!) Inhibitor forms treated with PLASMAPHERESIS!!! (inhibitor in blood floating around, just pull plasma and put fresh frozen plasma in then we can get rid of the inhibitor) Things like: • Malignancy • BM transplant • Pregnancy • Medications

We can also get Heparin-induced decreased platelets causing a TYPE II thrombocytopenia. What is the onset of this type? What is dangerous about this? What is this caused by? THIS CAN BE FATAL!!!, so what must we do? (KNOW THIS!!!) What drug if used lowers the risk in patients without previous Heparin-Induced Thrombocytopenia (HIT)?

» Onset at 5-14 days after commencement/starting of therapy (sometimes sooner if previously sensitized)!!! » Can lead to life-threatening thrombosis!!! (KNOW THIS!!!) » Caused by immune reaction directed against HEPARIN-PF4 COMPLEX!!! (PF4 is a anti-heparin factor) These immune complexes activate platelet aggregation, promoting thrombosis even in the setting of marked thrombocytopenia. (KNOW THIS!!) MUST discontinue heparin!!! » Use of LMWH!!! (remember TYPE II is the BAD ONE!!! and these people can never have heparin again)

When it comes to other coagulation system lab studies we use, there are some called MIXING STUDIES which we talked about before also. If we think someone has problems with some of the factors, we can do this test. What happens in this test?

» Patient's abnormal plasma is mixed (in varying proportions) with: • Normal plasma (contains all factors) • if correction — factor deficiency!!!! • if not — FACTOR INHIBITOR!!!! or HEPARIN. (KNOW THIS!!!) Abnormal plasma can be mixed with either of these two to narrow things down: • Serum [absent: I, II, V, VIII, XIII (consumable factors); contains VII, IX, X, XI, XII] • Absorbed plasma [absent: II, VII, IX, X (vitamin Kdependent factors); contains others like I, V, VIII, XI, XII, XIII]

Now lets talk about QUALITATIVE DISORDERS of Platelet abnormalities. What sorts of clinical clues lead us to the idea of Platelet dysfunction?

» Positive bleeding history!! » Prolonged bleeding time!! » Normal platelet count!!! (enough platelets, just not working though)

We can also have deficient production of platelets in the form of MARROW FAILURE or INJURY. We can get Hypoplasia or suppression of megakaryocytes, by what sorts of things and what is the most common cause? Replacement of marrow by what kinds of things can be seen? We can also get Ineffective Thrombopoiesis, what can cause this?

» Rarely congenital » Usually due to drugs, radiation, or toxins!!! (KNOW THIS!!!) » HIV infection Leukemic cells, metastatic carcinoma or fibrosis (myelophthisic process)!!! (leukoerythroblastosis, tear drops) The bone marrow here is making the platelets but they are bad so they are never released, we don't see any evidence of their production thus. Usually due to things like: » Megaloblastic anemia (B12/folate deficiency) » Myelodysplasia (show up as macrocytic, cytopenias) (both of these effect all cell lines)!!! (KNOW THIS!!!)

We can also have structural vascular abnormalities due to impaired vascular support for example collagen abnormalities. What are some diseases that we see this in?

» Scurvy!!! (KNOW THIS!!!) (SEE S88 for picture) (we see a big ecchymosis) » Excessive glucocorticosteroids!!! (KNOW THIS!!!) • Steroid therapy • Cushing disease » Senile purpura - increased vessel fragility from aging, sun exposure, etc.!! (S89) » Ehlers-Danlos syndrome!!!

In thrombocytopenia spontaneous bleeding usually doesn't become evident until when? What counts can aggravate post-traumatic bleeding? When there is spontaneous bleeding due to low platelets, what parts of the body are affected most?

» Spontaneous bleeding does not usually become evident until the count falls BELOW 20,000/mm3!!! (KNOW THIS!!!) » Counts in the range of 20-50,000/mm3 can aggravate post-traumatic bleeding » Spontaneous bleeding most often involves small vessels of skin (petechiae), mucous membranes of GI and GU tracts (hematuria, positive guiac) and intracranial hemorrhages!!! (KNOW THIS!!!)

Acquired platelet dysfunction can also be caused by what other things? (all the discussed platelet dysfunction disorders seen on S158!!!)

» UREMIA (pathogenesis is complex, but several platelet abnormalities are seen - defects in adhesion, granule secretion, and aggregation)!!! (abnormal bleeding time and platelet dysfunction in these) » Paraproteinemias (MYELOMA (like Waldenstroms and macroglobulinemia)!!! » Fibrin degradation products!!! - Anti-coagulative and anti-platelet properties » Myeloproliferative syndromes (increased platelets in this in most of them but in MF only early in disease)(risk for thromboses bc platelets actually not working), Myelodysplastic Syndromes, acute leukemias (stem cell disorders) » Liver disease (can affect platelet function)

Associated diseases are also important as many systemic diseases result in hemostatic defects, such as what? (KNOW THESE!!!) (Tests should be selectively ordered in accordance with the type of bleeding and the patient's history)

» Uremia (renal failure) (BUN and creatinine are elevated here; affects platelet function and other factors in body) » Hepatic disease (liver failure) (bc factors are being made here) » Infections (endotoxins activating coagulation and other infections) » Malignancies (AML-M3 can cause DIC bleeding disorders and other clotting disorders)

We have INHERITED qualitative platelet abnormalities, what are some of these? (KNOW THESE!!) What are the ACQUIRED ones due to?

» von Willebrand disease (vWD) - an abnormality of vWF causing what looks like platelet dysfunction!!! » Glanzmann thrombasthenia » Bernard-Soulier syndrome » Thrombopathies » Drugs » Other like uremia, other disease states

We have various subsets of ITP!! There are two typical clinical settings with some overlap. There is a CHILDHOOD or ACUTE form usually in children!!! It affects male kids as much as female kids. What does it frequently follow? What do we see? Is it self-limited? What can 20% of them develop? There is also a CHRONIC form which is the ADULT form. Who is this most common in? What is the onset like and the thrombocytopenia? What do we use to treat the chronic form? In both of these settings clinically what does the SPLEEN look like? How do the platelets look? How do we usually diagnose ITP?

• Frequently follows an INFECTION (~2 weeks) • Severe thrombocytopenia <20,000/mm3!!! • Self-limited — most patients spontaneously recover in 6 weeks to 6 months!!! • Up to 20% may develop a picture of CHRONIC ITP (usually without viral prodrome). • Most common in YOUNG FEMALES (<40 y/o)!!! • Female:male = 3:1!! • INSIDIOUS/SLOW onset NOT following an infection and Moderate thrombocytopenia 30 to 80,000/ mm3!!! • Chronic course frequently requiring STEROIDS and/or splenectomy, IV Ig!!! or anti-CD20!!! • Spleen is NORMAL to mildly enlarged!!! • Platelets may be ENLARGED (young, ↑ MPV)!!! • Bone marrow megakaryocytes are often SLIGHTLY INCREASED in number with immature forms (not a marrow problem; look in marrow, there are plenty of platelets and mean platelet volume is enlarged, meaning young platelets out there which is usually ITP) • Anti-platelet antibody tests are often positive, but are not widely available and suffer from poor sensitivity and specificity Usually a DIAGNOSIS OF EXCLUSION (must exclude all other causes of thrombocytopenia)!!!

The Inherited disorder of vWF is von Willebrand Disease (vWD)!!! What do we know about this disorder? How many variants can we see? Clinically what is the picture? What do we know about the symptoms and lab tests in different people?

• Most COMMON INHERITED BLEEDING DISORDER of humans; 1% of adults in US!!! (KNOW THIS FACT!!!) • More than 20+ variants described; most are AUTOSOMAL DOMINANT; rare autosomal recessive variants. Most are due to reduced quantity, others are qualitative problems. It looks like a platelet dysfunction disorder but it is actually the vWF that is the problem. We see bleeding symptoms are platelet related (epistaxis, bruising, menorrhagia at menarche); rarely looks like a hemophilia bc hemophilia A is supposed to be low factor 8, so possible since 8 also is associated with vWF! Symptoms and lab test results VARY from individual to individual in a kindred and WITHIN individuals from time to time!!!! (KNOW THIS!!!); many improve with increased age; some are nearly asymptomatic (additional genetic factors influence circulating levels). (SEE S149 for a list of these, we will talk about TYPE 1 type which give the TYPICAL PRESENTATION, it is 70-80% of cases of vWD)(S150 shows the electrophoresis that is used to do the work up of vWD, shows the multimeric anlaysis with multimeres in different patterns depending on the type)

When it comes to platelet abnormality disorders that are quantitative disorders, we have disorders that have ACCELERATED DESTRUCTION due to consumption of platelets!!! What are the 3 major disorders known to have consumption of platelets!! In the book there are 2 of them that they refer to as Thrombotic Microangiopathies, which we also considered as MAHA's in the RBC section, what are these and what is going on in them? (These ARE NOT COAGULATION problems, so PT and PTT would be normal) What about DIC, which is considered to be the third one? What do all 3 of these display?

• Thrombotic thrombocytopenic purpura (TTP) • Hemolytic-uremic syndrome (HUS) -in both of these we see platelets start aggregating and there is a thrombocytopenia. Both show widespread formation of hyaline thrombi in the microcirculation composed of platelet aggregatation (and fibrin) → this leads to microangiopathic hemolytic anemia and consumption of platelets!!! We do see SCHISTOCYTES here. (BOTH THINGS happen) (Presentation of these two diseases can be very similar) DIC has both PLATELET and COAGULATION FACTOR CONSUMED/lost control of coagulation so there is also a coagulation issue with it. So there will be ELEVATED PT and PTT!!! (it is a consumption coagulopathy; thus, discussed in detail later in coagulation section) All display a Microangiopathic Hemolytic Anemia (will see schistocytes) with Thrombocytopenia!!! (KNOW THIS FACT!!!!)